Method for hydrodynamic impingement on a web continuous material with water jets and nozzle beams for producing liquid jets

ABSTRACT

The nozzle beam on a device for producing liquid jets in order to impinge said jets upon the fibres of a web of continuous material guided along the beam consists of a beam housing extending along the working width of the continuous web of fibre material, whereby two longitudinal bores placed on top of each other are accommodated in said housing and are separated from each other by means of an intermediate wall provided with continuous boreholes. The nozzle strip required to produce the liquid jets is mounted in a liquid-tight manner in the lower part of the housing and is cross-flown by pressurized water. In order to enable more needle water to reach the fabric than is usual with such a construction, two strips of nozzles are mounted in a housing and must be provided accordingly with pressurized water. This construction also makes it possible to arrange a larger number of nozzle strips and therefore nozzle jets on a drum, which is advantageous with respect to the various needling effects obtained with a nozzle beam.

The invention relates to a method for hydrodynamically impingingnonwovens, tissues, woven fabric, or knitted fabric with fluid jetswhereby a fluid is sprayed under a high pressure of up to 1,000 bar fromfine jet orifices arranged tightly spaced in a row within a jet strip ofa jet manifold extending over the working width against the fabric webadvancing opposite the jet manifold.

U.S. Pat. No. 4,870,807 discloses an approach whereby a row of jet holesis arranged side by side and spaced extremely tightly together within ajet strip, possibly also providing for two rows of orifices arrangedside by side, the orifices being distributed in staggered fashion overthe length of the jet strip. This approach provides a water curtain ofuninterrupted water jets arranged side by side, thereby also essentiallyavoiding a line marking due to the indentation action of a particularwater jet on the fabric web. The water jets are formed in preciselyfabricated orifices within the jet strip; U.S. Pat. No. 3,403,862 may bereferred to in this regard.

In many applications, it is advantageous to have a larger volume ofwater to create the desired effect on the fabric web. This is true, forexample, for the fabrication of perforated nonwovens by means ofhydrodynamic needling. However, it is not desirable to enlarge thediameter of the jet holes to allow passage of more water since theeffective action of the water jet simultaneously with the desiredcompaction of the nonwoven is thereby reduced.

On the other hand, approaches may be conceived whereby these jets impacta fabric web in a configuration in which the jet holes are arrangedwithin a jet strip immediately back to back but with greater spacingthan with two rows of possibly staggered jet holes; and in which thenecessarily required spacing of two complete side-by-side jet manifoldsis too large.

The goal of the invention is therefore to find a solution in which alarger volume of fluid, or multiple tightly spaced jets, may be appliedto the fabric using a conventional jet manifold with jet strips mountedin a sealed manner within this manifold. To achieve this solution, theinvention provides that the sprayed fluid be distributed, in anunmodified manner, uniformly over the working width of the fabric web,but that more than one water jet simultaneously impact a small region ofthe advancing fabric web in a back-to-back orientation in the directionof transport. This means that, advantageously, a greater volume of fluidmay be sprayed onto a particular impact site, or multiple impact sites,on the fabric web simultaneously by multiple water jets from multiplejet strips—as viewed in the direction of the advancing fabric web. It isalso conceivable in this approach that more than one water jetsimultaneously impact a small region between 1 cm and 20 cm, preferably8 cm, of the advancing fabric web in line back-to-back in the directionof transport.

These ideas differ from the solutions of U.S. Pat. No. 3,214,819 or U.S.Pat. No. 3,873,255. These disclose manifolds which extend over theworking width of the fabric web. The previously known individual jetsare arranged in part in opposing fashion, thereby also spraying water inconcentrated form onto one location of the advancing nonwoven web, butin fact in point form onto one location, not over the entire workingwidth. Even if the jets extended in slit form over the working width,this idea could not be transferred to the invention. The approach hereinvolves the generation of fine jets, and is possible only using thepreviously known jet manifold design including pressure chambers andpressure distribution chambers. If the idea of the two US documents weretransferred to the jet manifold required here according to U.S. Pat. No.5,870,807, the effect according to the invention could not be achieved;the dimensions of the interfering housings would obstruct each other.

Using the idea according to the invention of generating multiple waterjets arranged in one jet manifold arranged back-to-back in the directionof transport also allows various effects, such as patterns, to beobtained. In the case in which the jet manifold oscillates at a definedfrequency, lines and indentations are pressed into the fabric web byeach jet, thus enabling a complete pattern to be created. Since thewater jets emerge from one jet manifold with a defined spacing, and thejet manifold oscillates at a defined frequency, two lines each are drawnback-to-back in the fabric web which, depending on the speed of thefabric web, may even be used to complete, for example, a braidedpattern, that is, a pattern with staggered crossing serpentine lines.This is also true for two back-to-back emerging water jets, and ofcourse even for a multiple of this, where the jet orifices are thenincorporated laterally side by side in the jet strip.

A jet manifold is composed of an upper section extending over theworking width of the web, and a lower section, wherein a pressurechamber of round cross-section extends over the length of the uppersection, to which chamber the fluid is fed under pressure, for example,at the front end; wherein a pressure distribution chamber is provided inparallel to said chamber behind a partition in the lower section, thepressure distribution chamber being connected to the pressure chamber byfluid passages located in the partition; and wherein additionally thejet strip with the orifices is mounted in fluid-tight fashion in thelower section.

A jet manifold of this type is known from European Patent A-0 725 175.Compared to the designs of U.S. Pat. No. 4,069,563 or GDR Patent A-220060 or German Patent C-37 27 843, this manifold has the advantage of asimpler design and less anticipated downtime for maintenance. Thisdesign ensures a uniform distribution of fluid over the length of thejet strip.

Only a limited peripheral region is available over the circumference ofthe drum transporting the fabric web during needling, especially in thecase of meander-type web routing. However, multiple jet manifolds arerequired to obtain the desired treatment effect. These jet manifoldsrequire a certain irreducible area in the circumferential direction,with the result that there is a maximum number of jet manifolds perdrum.

In addition, only a limited volume of fluid per jet manifold may beapplied to the web. For many treatment processes, however, this volumeis insufficient, for example, to produce holes in the nonwovens wherethe individual fibers must be flushed with a large amount of waterflowing through the nonwoven at the edges of the holes, that is, at oneand the same location of the drum or of the nonwoven. In this case, itis also not possible to increase the number of jet manifolds at multipledrums extending the length of the overall unit, since only one drum,such as that in European Patent A-1 001 064, with pins for the holes,may be employed to produce the holes.

These problems may be solved by mounting two jet strips with orificesfor the jet holes in the housing forming the jet manifold, the two jetstrips being advantageously located close together in the housing of thejet manifold. This approach eliminates at least one wall of theotherwise two adjacent jet manifolds which must be attached toaccommodate the water connections as well as attached with a separationbetween them within the machine frame. To achieve an optimal design, onepressure chamber followed by one pressure distribution chamber eachshould be allocated within the one jet manifold housing to the two jetstrips to supply and distribute the fluid, the two pressure distributionchambers, or possibly pressure chambers as well, being arranged closetogether in the housing of the jet manifold. With this type of “duplex”jet manifold, multiple jet strips may be located at least over theavailable circumference of a drum, such as a pin-type drum; in otherwords, multiple water jets may be involved.

This design may also be used to affect the circumferential spacing ofthe water jets striking the fabric web. In addition to the fact thatwith two jet strips arranged closely together in one jet manifold, thedistance to the following water jet curtain is closer, the two lines ofthe pressure distribution chambers arranged back-to-back along withtheir associated jet strips may be oriented obliquely relative to eachother in the one jet manifold housing such that the water jets strikingthe fabric web are directed in an arrow shape toward each other, andthereby disposed even closer together at the impact site. The interfaceof the two jets generated in one housing with the two jet strips mayeither be on the fabric itself or behind the fabric. Of course, it isalso possible to match the inclination of the fluid jets configured inan arrow shape only to the diameter of the drum located directly underthe jet manifold and transporting the fabric web, such that the waterjets always impact the fabric web vertically.

If the goal is to have the water jets from two jet strips impact thefabric web very closely together, or even touch, it is advantageous toemploy only one pressure chamber in the jet manifold for the two jetstrips, and to control this pressure chamber orifice by the particularfluid passages in a two-fold manner.

The drawings illustrate the functional principle of a jet manifoldaccording to the invention.

FIG. 1 is a section through a “duplex” jet manifold;

FIG. 2 is also a section through a “duplex” jet manifold with jetsdirected obliquely toward each other; and

FIG. 3 is also a section through a “duplex” jet manifold, but havingjets directed toward each other so that the jets meet at the fabric web.

In principle, a jet manifold is composed of components as described inEuropean Patent A-0 725 175. For this reason, the disclosure of EuropeanPatent A-0 725 175 is referenced here.

A jet manifold is composed of a housing 1 with two longitudinal orifices2 and 3. The two longitudinal orifices 2, 3 are separated by a partition4 in which the passages 5 connecting orifices 2, 3 are located. Oppositethese passages and in line on the other side of orifice 3 is a narrowerslit 6 from which the fluid emerges. A jet manifold of this basic designis also advantageous here in unmodified form. Water under a highpressure of up to 1000 bar enters at the front side of orifice 2, whichacts as a pressure chamber, in the upper section of the housing; thewater is distributed along the entire length of the jet manifold throughpassages 5 into the pressure distribution chamber 3 located in the lowersection of the housing. In the device shown, a base component having aplurality of bolts, not shown here, is attached to the bottom of housing1. The jet strip 7 required to generate the fluid jets is mounted in agroove 8 in the base component. The fluid jets then emerge from the jetmanifold through slit 9 in the center below jet strip 7 and impact thefabric web transported on, for example, the drum 10.

In the jet manifold of FIG. 1, two orifices 2 and 2′ for the pressurechambers, and two orifices 3 and 3′ for the pressure distributionchambers, have been incorporated into housing 1. As a result, two jetmanifolds with all the orifices and components described are essentiallylocated in one housing 1, with the result that there is a savings of onehousing. The new housing of FIG. 1 is in fact somewhat larger in itslateral dimensions, but smaller than the two manifolds in the previouslyknown design.

Based on this design of a jet manifold, the two jet strips 7 and 7′ arespaced much closer together than is the case with two jet manifolds, andas a result, more jet strips may be located on one drum 10, and thusmore generatable fluid jets 11 may impact the drum than in previouslyknown approaches.

The design of FIG. 1 is employed when the fabric web is routed on asingle horizontally moving belt. If the web is routed over a drum, thenthe design of FIG. 2 is recommended in which the water jets from the twojet strips 7, 7′ impact the fabric web vertically even with this routingover a drum. This result is made possible by having the pressurechambers 2 and 2′ remain unchanged, but by boring the two pressuredistribution chambers 3″, 3′″ in a mutually offset fashion such that thepassages 5″ and 5′″, and slits 6″ and 6′″ are oriented in line in anarrow-shaped configuration toward each other.

The jet manifolds of FIGS. 1 and 2 may also be employed to produce aline pattern with a variety of individually recognizable lines. For thispurpose, manifold 1 should preferably oscillate at a defined frequencyof up to 50 Hz, preferably at 20 Hz. Since the water jets from the twojet strips 7, 7′ impact the fabric web in a timewise-staggered fashion,due to their spacing relative to the advancing fabric web, any type ofline pattern may be imprinted into the fabric web by the water jets whenthe manifold is oscillating. To this end, the jet strips may also beprovided with a special perforation having jet holes or groups of holeswith greater spacing. The perforation may also begin at the end of thestrip at varying distances to the extreme end—in other words, thezero-point setting may vary. In addition, it is possible to produce twodifferent types of needling with one jet manifold. The first jet stripmay be used to produce a full two-dimensional needling of the nonwovenproduct, and the second jet strip may be employed to impart a pattern,for example, a striped pattern with parallel lines of whatever typedesired.

In the case of an inclination of the water jets in an arrow-shapedorientation toward each other, this inclination may be increased, asshown in FIG. 3, by orienting the lines of back-to-back components 6″,3″, 5″ and 2, and analogously, 6′″, 3′″, 5′″ and 2′, in a correspondingarrow-shaped configuration in housing 1, thereby creating theprerequisite for the water jets 11 generated at jet strips 7, 7′ to meetat the fabric on drum 10 due to the now possible greater inclination.Instead of two pressure chambers 2 and 2′, one pressure chamber may besufficient for this design, the two passages 5″ and 5′″ entering thispressure chamber. This is, of course, also possible with otherembodiments. The result is a method in which it is possible to applymore water than previously known simultaneously to one and the samepiece of fabric by employing sharply defined, bundled water jets from ajet manifold.

1. Method for hydrodynamically impinging nonwovens, tissues, wovenfabric, or knitted fabric with fluid jets, comprising spraying a fluidunder a high pressure of up to 1000 bar from fine jet orifices arrangedtightly spaced in rows within a plurality of jet strips of a jetmanifold extending over a working width against a fabric web advancingopposite the jet manifold, wherein the sprayed fluid is distributeduniformly in an unmodified fashion over the working width of the fabricweb, but is delivered to each of the plurality of jet strips by one of aplurality of pressure distribution chambers, the pressure distributionchambers being arranged side-by-side in a single jet manifold so that atleast two fluid jets simultaneously impact a small region of theadvancing fabric web in a back-to-back orientation in the direction oftransport.
 2. Method according to claim 1, wherein the at least twofluid jets simultaneously impact a small region between 1 cm and 20 cmof the advancing fabric web in line back-to-back in the direction oftransport.
 3. Method according to claim 1, wherein a large volume offluid is sprayed simultaneously from multiple water jets emerging fromone jet manifold onto one impact site on the fabric web.
 4. Methodaccording to claim 1, wherein different patterns are applied to thefabric web using one jet manifold.
 5. Method according to claim 1,wherein the one jet manifold is moved back and forth in its longitudinaldirection.
 6. Method according to claim 5, characterized in that the onejet manifold moves at a rate between 5 Hz and 50 Hz.
 7. Method accordingto claim 5 wherein, depending on the speed of the advancing fabric web,different patterns are pressed into the fabric web by the fluid jetsfrom the jet orifices.
 8. Jet manifold on a device for generating fluidjets for jet impingement of fibers of a web transported along themanifold by a drum or continuous belt, comprising a single housinghaving an upper section extending over the working width of the web anda lower section; a plurality of pressure chambers of round cross-sectionover their length located in the upper section, each of the pressurechambers supplying fluid under pressure; a plurality of pressuredistribution chambers provided in parallel to the pressure chambers inthe lower section behind a partition, each of the pressure distributionchambers being connected to each of the pressure chambers by a fluidpassage located in the partition; and a plurality of strip-shaped jetplates having orifices for the fluid jets mounted in the lower section,each of the jet plates being connected to each of the pressuredistribution chambers.
 9. Jet manifold according to claim 8, wherein theplurality of jet strips are spaced close together at a distance ofbetween 0.5 cm and 20 cm.
 10. Jet manifold according to claim 8,wherein, within the single housing, two lines of pressure chambers, twopressure distribution chambers, and two jet strips are provided.
 11. Jetmanifold according to claim 10, wherein the two pressure chambers andpressure distribution chambers are spaced close together within thesingle housing of the jet manifold.
 12. Jet manifold according to claim10, wherein the two lines of pressure chambers and pressure distributionchambers, along with the associated passages, are oriented adjacent toeach other in parallel within the single housing, whereas axes of theorifices of one of the jet strips are oriented obliquely toward axes ofthe orifices of another of the jet strips such that the fluid jetsimpacting the fabric web are directed toward each other in anapproximately arrow-shape configuration.
 13. Jet manifold according toclaim 10, wherein the two lines of pressure chambers and pressuredistribution chambers along with axes of the orifices of the associatedjet strips are oriented obliquely toward each other within the singlehousing, such that the fluid jets impacting the fabric web are directedtoward each other in an approximately arrowshape configuration.
 14. Jetmanifold according to claim 13, wherein the jets from the two adjacentjet strips impact the fabric web based on the orientation of the jetstrips in the single housing.
 15. Jet manifold according to claim 13,wherein the jets of the two adjacent jet strips in the one jet manifoldmeet behind the fabric web based on the orientation of the jet strips inthe jet manifold.
 16. Jet manifold according to claim 13, wherein aninclination of the fluid jets directed toward each other in an arrowshape are matched to a diameter of the drum relative to the fabric webimmediately below the jet manifold provided with two jet strips, andtransporting the fabric web, such that the jets impact the fabric webvertically.
 17. Jet manifold according to claim 8, wherein the jetstrips are provided with orifices spaced at a greater distance ofbetween 1 mm and 20 mm.
 18. Jet manifold according to claim 17, whereina group of multiple orifices are located immediately adjacent to eachother, but that this group in turn is separated from another group by agreater distance of between 1 mm and 20 mm.
 19. Jet manifold accordingto claim 8, wherein the orifices of the jet strips arranged back-to-backin the direction of transport are arranged in a staggered orientationadjacent to each other.
 20. Jet manifold according to claim 19 whereinorifices of a first jet strip are arranged with respect to orifices of asecond jet strip such that a lateral zero position of the orifices ofthe first jet strip is laterally offset relative to those of the secondjet strip, but are otherwise provided with the same spacing.
 21. Jetmanifold according to claim 10, wherein the two jet strips comprise afirst jet strip of tightly spaced jet holes for two-dimensionalneedling, and a second jet strip transport with jet holes which areincorporated with greater spacing so as to produce a line pattern.